Free insert mailers are known, as for example described in my International Patent Application WO-A-9321022. In general, removal of a tear-off stub portion along one side of the mailer allows free withdrawal of the inner ply or plies which are not otherwise attached to the assembly. A basic free insert mailer may comprise front and back outer plies which comprise the envelope, and inner plies comprising for example business forms. Two inner plies may be superimposed and glued together to form a smaller return envelope. This is not a prefolded envelope but may comprise a foldable closure flap. The inner plies may for example be die cut or chipped on three sides so that glue lines running transverse of the web to join the outer plies do not attach the inner plies, which are normally glued longitudinally along a fourth side to attach to the stub portion.
It will be appreciated that the multiple ply assembly is constructed from a plurality of webs which are generally pre-printed and subjected to successive and various transverse and longitudinal chipping, glueing, slitting and perforating steps during collation. The final collated assembly may, for example, be folded in a zig-zag fashion for delivery to a customer. The mailers when still connected may be run at speed through a computer printer before final separation.
However, the webs employed in the construction of the outer envelope and free inserts are normally of substantially the same width. This means that the inserts must comprise either single sheets, or single sheets attached together in a further glueing step as in the case of an inserted return envelope, of no greater width than the outer webs comprising the envelope proper. In other words, it has not been attempted to include a folded insert sheet of say twice the width of the outer plies in its unfolded condition, since this would involve the introduction of a web of substantially different width out of register with the other plies and necessarily involves a difficult folding operation. Nevertheless, the advantages of such an insert must be evident; a four-page form, promotional sheet or brochure can be printed on two sides of a single web; a folded insert is easier to read and allows more flexible graphic layout design on the side opened out; opening a folded insert to lie flat is possible, whereas two sheets placed one above the other and glued along one side are difficult to open out and to lie flat and may become detached; a folded insert designed as a brochure has a better appearance and does not have the feel and look of a business form.